The NIH Consensus Statement on Rehabilitation of persons with TBI states that "the neurobiology of TBI in humans should be studied with modern imaging techniques and correlated with neuropsychological findings." Similarly, the need to integrate neuroimaging research with neuropsychological assessment has been recognized by the NCMRR as they encourage research correlating imaging and behavioral variables, such as neuropsychological assessment. Memory deficits are among the most frequently reported and most severe problems following TBI and can persist years after injury. While much research has documented the presence of memory impairments in TBI, the specific cognitive mechanisms of such impairments are not yet well understood. Work has shown that memory difficulties evidenced in TBI may be primarily attributable to deficits in the acquisition or encoding of information rather than retrieval of information from long-term storage. Understanding why persons with TBI experience difficulty in the acquisition or encoding of information is of critical importance. A major aim of the present study is to examine factors that influence the encoding of information. Because of its influence on the encoding of learned material, it is critical to relate behavioral data regarding organizational strategies with alterations in cerebral substrates in persons with TBI. While behavioral data clearly indicate that organization and executive control impact and may disrupt memory, the cerebral substrates are unknown. To date, there are no functional neuroimaging studies examining the impact of organizational strategies on encoding in TBI. A purpose of this study is to address this critical void. The investigators will use BOLD fMRI to examine the effects of TBI on encoding using paradigms that have been established in healthy individuals. Participants will be 40 persons with moderate-severe TBI (20 with significant executive dysfunction; 20 with minimal dysfunction) and 20 healthy controls. It is expected that TBI subjects will show more widespread activation during encoding tasks requiring greater executive control compared with healthy controls. It is expected that this effect will be greatest in TBI subjects with significant executive dysfunction. The results of the present study will provide a better understanding of the specific mechanisms of encoding and the impact of executive control on memory and may provide tools to develop more effective intervention and rehabilitation.